You're going to have to be more specific with the games you're playing. You may just want to go with a Sandy Bridge or Ivy Bridge CPU as your current CPU is already overclocked. Not much more can be done with your current CPU.

1. Lower the calculation settings of the game (Cars, Elements, Physics)
2. Overclock even higher
3. Disable C-states (decreases latency) - can give a noticeable boost
4. Run your system as lean as possible - (no services that you don't need/ no background software etc)
5. Tweak your ram timings/ speed.
6. set the game to realtime priority in task manager.

Also good things to do:
- Check if your game is really cpu limited (maxed out CPU util%?)
- Bench your CPU to make sure the numbers look right(stable OC? mb acting funky? etc)
- Make sure you're not throttling during games (use a temp logging tool/clockspeed logging tool)
- Check your power settings in windows control panel, make sure that max CPU is set to 100% in profile

Finally (last but not least)
- Google for a tweak guide of the game: games use a bunch of stuff that is unnoticeable to the player but can make a HUGE difference in performance (like in oblivion where the shrubs wind effect was calculated so far from the player you could barely see) - a simple .ini edit could make a massive difference in FPS.

This is a bad recommendation. Setting a game to real time (if CPU bound) will give the game precedence over a lot of Windows services. It is very possible that if your CPU gets fully loaded that your machine could crash from setting the game to realtime (there is also a very good bet that it won't let you do this.) Setting it to "High" and making sure that the CPU affinity is set to all cores (which it usually is by default.)

If your machine is at 0-2% when you're idling, removing services won't do anything for you and is a moot point.

Have you verified that your CPU is your bottleneck? With my Phenom II 940 I was occasionally bottle-necking on memory (DDR2) and not the CPU or GPU where other games will tax the GPU or CPU more. So I would do some testing and gather some empirical data to determine what is really slowing your machine down in certain games.